Finely dispersed emulsifier-free systems of the oil-in-water and water-in-oil type

ABSTRACT

Cosmetic or dermatological preparations, which are finely dispersed systems of the oil-in-water or water-in-oil type, comprising 
     1. an oil phase, 
     2. an aqueous phase, 
     3. at least one modified polysaccharide which 
     (a) has both hydrophilic and lipophilic properties, i.e. has amphiphilic character, and is thus dispersible both in water and in oil, and which 
     (b) has no thickening properties, and 
     4. at most 0.5% by weight of one or more emulsifiers. 
     and also 
     optionally comprising further cosmetic or pharmaceutical auxiliaries, additives and/or active substances.

The present invention relates to emulsifier-free finely dispersedsystems of the oil-in-water and water-in-oil type, preferably ascosmetic or dermatological preparations.

Emulsions are generally taken to mean heterogeneous systems whichconsist of two liquids which are immiscible or have only limitedmiscibility with one another, which are usually referred to as phases.In an emulsion, one of the two liquids is dispersed in the form of veryfine droplets in the other liquid.

If the two liquids are water and oil and if oil droplets are finelydispersed in water, then this is an oil-in-water emulsion (O/W emulsion,e.g. milk). The basic character of a O/W emulsion is defined by thewater. In a water-in-oil emulsion (W/O emulsion, e.g. butter), theprinciple is reversed, the base character here being determined by theoil.

In order to achieve permanent dispersion of one liquid in another,emulsions in the traditional sense require the addition of aninterface-active substance (emulsifier). Emulsifiers have an amphiphilicmolecular structure, consisting of a polar (hydrophilic) and a nonpolar(lipophilic) molecular moiety, which are spatially separate from oneanother. In simple emulsions, finely dispersed droplets of one phase,surrounded by an emulsifier shell, (water droplets in W/O emulsions orlipid vesicles in O/W emulsions) are present in the second phase.Emulsifiers lower the interfacial tension between the phases bypositioning themselves at the interface between the two liquids. At thephase boundary, they form oil/water interfacial films, which preventirreversible coalescence of the droplets. Emulsions are frequentlystabilized using emulsifier mixtures.

Traditional emulsifiers can, depending on their hydrophilic molecularmoiety, be divided into ionic (anionic, cationic and amphoteric) andnonionic:

The most well known example of an anionic emulsifier is soap, which isusually the term used for the water-soluble sodium salts or potassiumsalts of saturated or unsaturated higher fatty acids.

Important examples of cationic emulsifiers are quaternary ammoniumcompounds.

The hydrophilic molecular moiety of nonionic emulsifiers frequentlyconsists of glycerol, polyglycerol, sorbitans, carbohydrates andpolyoxyethylene glycols, and, in most cases, is linked to the lipophilicmolecular moiety via ester and ether bonds. The lipophilic molecularmoiety usually consists of fatty alcohols, fatty acids or isofattyacids.

By varying the structure and the size of the polar and nonpolarmolecular moiety, the lipophilicity and hydrophilicity of theemulsifiers can be varied within wide limits.

A decisive factor for the stability of an emulsion is the correct choiceof emulsifiers. The characteristics of all substances present in thesystem are to be taken into consideration. In the case of, for example,skin care emulsions, polar oil components and, for example, UV filterslead to instability. As well as the emulsifiers, therefore, otherstabilizers are also used which, for example, increase the viscosity ofthe emulsion and/or act as a protective colloid.

Emulsions are an important type of product in the field of cosmeticand/or dermatological preparations.

Cosmetic preparations are essentially used for skin care. The main aimof skin care in the cosmetics sense is to strengthen or rebuild theskin's natural function as a barrier against environmental influences(e.g. dirt, chemicals, microorganisms) and against the loss ofendogenous substances (e.g. water, natural fats, electrolytes). If thisfunction becomes impaired, increased resorption of toxic or allergenicsubstances or infection by microorganisms may result, leading to toxicor allergic skin reactions.

Another aim of skin care is to compensate for the loss by the skin ofgrease and water caused by daily washing. This is particularly importantif the natural regeneration ability is inadequate. Furthermore, skincare products should protect against environmental influences, inparticular against sun and wind, and delay skin ageing.

Cosmetic preparations are also used as deodorants. Such formulations areused to control body odour which is produced when fresh sweat, which isin itself odourless, is decomposed by microorganisms.

Medicinal topical compositions usually comprise one or more medicamentsin an effective concentration. For the sake of simplicity, in order todistinguish clearly between cosmetic and medicinal use and correspondingproducts, reference is made to the legal provisions in the FederalRepublic of Germany (e.g. Cosmetics Regulation, Foods and Drugs Act).

The use of customary emulsifiers in cosmetic or dermatologicalpreparations is in itself acceptable. Nevertheless, emulsifiers, likeultimately any chemical substance, may in certain circumstances causeallergic reactions or reactions based on oversensitivity of the user.

For example, it is known that certain light dermatoses are triggered bycertain emulsifiers, but also by a variety of fats and simultaneousexposure to sunlight. Such light dermatoses are also-called “Mallorcaacne”. There has thus been no lack of attempts to reduce the amount ofcustomary emulsifiers to a minimum, in the ideal case even to zero.

A reduction in the required amount of emulsifier can, for example, beachieved by taking advantage of the fact that very finely divided solidparticles have an additional stabilizing action. The solid substanceaccumulates at the oil/water phase boundary in the form of a layer, as aresult of which coalescence of the dispersed phases is prevented. It isnot the chemical properties of the solid particles which are offundamental importance here, but the surface properties.

Around 1910, Pickering prepared paraffin/water emulsions which werestabilized merely by the addition of various solids, such as basiccopper sulphate, basic iron sulphate or other metal sulphates. This typeof emulsion is thus also referred to as a Pickering emulsion. For thistype of emulsion, Pickering postulated the following conditions:

(1) The solid particles are only suitable for stabilization if they aresignificantly smaller than the droplets of the inner phase and do nothave a tendency to form agglomerates.

(2) An important property of an emulsion-stabilizing solid is also itswettability. i.e. in order to stabilize an O/W emulsion, the solid has,for example, to be more readily wettable by water than by oil.

The original forms of Pickering emulsions initially surfaced, as itwere, as undesired secondary effects in a variety of industrialprocesses, such as, for example, in secondary oil recovery, theextraction of bitumen from tar sand and other separation processesinvolving two immiscible liquids and fine, dispersed solid particles.These are generally W/O emulsions which are stabilized by mineralsolids. Accordingly, investigation of corresponding systems, such as,for example, the oil/water/soot or oil/water/slate dust systems wasinitially the focus of research activity.

Basic experiments have shown that one characteristic of a Pickeringemulsion is that the solid particles are arranged at the interfacebetween the two liquid phases where they form, as it were, a mechanicalbarrier against the mixing of the liquid droplets.

It is a relatively new technical development to use Pickering emulsionsas a base for cosmetic or dermatological preparations.

One way of achieving solids stabilization in a cosmetic ordermatological preparation is, according to May-Alert (Pharmazie inunserer Zeit [Pharmacy in our time], Vol. 15, 1986, No. 1, 1-7) forexample, to use emulsifier mixtures which contain both anionic andcationic surfactants. Since mixing anionic and cationic surfactantsalways produces precipitates of insoluble, electroneutral compounds,deliberate precipitation of these neutral surfactants in the oil/waterinterface makes it possible to achieve additional solids stabilizationin the sense of a Pickering emulsion.

EP-A-0 686 391 describes water-in-oil emulsions which are free fromsurface-active substances and are stabilized only by solids.Stabilization is achieved here using spherical polyalkylsilsesquioxaneparticles which have a diameter of from 100 nm up to 20 μm. According tothe above, these emulsions can be referred to as Pickering emulsions.

In addition to the described Pickering emulsions, the prior artdescribes further emulsifier-free, finely dispersed cosmetic ordermatological preparations which are generally referred to ashydrodispersions. Hydrodispersions are dispersions of a liquid,semi-solid or solid internal (discontinuous) lipid phase in an outeraqueous (continuous) phase.

In the case of hydrodispersions of a liquid lipid phase in an outeraqueous phase, stability can be ensured, for example, by constructing,in the aqueous phase, a gel structure in which the lipid droplets arestably suspended. DE-A 44 25 268 describes stable finely dispersed,emulsifier-free cosmetic or dermatological preparations of theoil-in-water type, which, in addition to one oil phase and one waterphase, comprise one or more thickeners from the group consisting ofacrylic polymers, polysaccharides and alkyl ethers thereof, where thesethickeners must not cause any lowering of the interfacial tension.

Using similar hydrodispersions as a basis, DE-A 43 03 983 disclosescosmetic or dermatological light protection formulations which areessentially free from emulsifiers, and which have inorganicmicropigments incorporated into the lipid phase of the hydrodispersion,which act as UV filter substances.

The object of the present invention was to extend the prior art toinclude cosmetic or dermatological preparations in which it is notnecessary to use any emulsifiers of a conventional type.

Surprisingly, this object is achieved by cosmetic or dermatologicalpreparations which are finely dispersed systems of the oil-in-water orwater-in-oil type, comprising

1. an oil phase,

2. an aqueous phase,

3. at least one modified polysaccharide which

a) has both hydrophilic and lipophilic properties, i.e. has amphiphiliccharacter, and is dispersible both in water and in oil, and which

b) has no thickening properties, and

4. at most 0.5% by weight of one or more emulsifiers

and also

optionally comprising further cosmetic or pharmaceutical auxiliaries,additives and/or active substances.

According to the invention, it is particularly advantageous if thepreparations comprise significantly less than 0.5% by weight of one ormore emulsifiers. Very particular preference is given to preparationsaccording to the invention which are entirely free from emulsifiers inthe traditional sense.

The preparations according to the invention are mixtures of oils oroil-soluble substances and water or water-soluble components, which arestabilized by adding modified polysaccharides and which do not have tocontain an emulsifier in the traditional sense. Stabilization isachieved by the modified polysaccharides attaching themselves to thedroplets of the disperse phase and forming, as it were, a mechanicalbarrier, which prevents coalescence of the droplets.

It was particularly surprising that the preparations according to theinvention can be formulated in a stable manner even without the additionof further stabilizers, in particular even without the addition ofhydrocolloids. Hydrocolloids are macromolecules which have a largelylinear structure and have intermolecular forces of interaction whichpermit secondary and primary valence bonds between the individualmolecules and thus the formation of a reticulated structure. Some arewater-soluble natural or synthetic polymers which, in aqueous systems,form gels or viscous solutions.

It was particularly surprising that in the preparations according to theinvention it is possible to dispense with any use of acrylate-alkylacrylate copolymers, in particular those from the group of so-calledcarbomers or Carbopois (Carbopol® is actually a registered trade mark ofB.F. Goodrich Company).

The preparations according to the invention are extremely satisfactorypreparations in every respect, whose aqueous/fatty phase ratio can bevaried within extraordinarily wide limits and, in addition, have theadvantage over the prior art that large amounts of oils can be stablyincorporated in water. It was also surprising that by following theteaching disclosed here as regards technical handling, it is possible toprepare water-in-oil Pickering emulsions and also oil-in-water Pickeringemulsions.

The water phase proportion of the W/O Pickering emulsions according tothe invention is preferably chosen from the range from 0.5 to 75% byweight, based on the total weight of the formulations.

The fatty phase proportion of the O/W Pickering emulsions according tothe invention is preferably chosen from the range from 5 to 75% byweight, very particularly advantageously from the range from 10 to 70%by weight, in each case based on the total weight of the formulations.

For the purposes of the present invention, modified polysaccharides areobtainable, for example, by reacting starch with mono- , bi- orpolyfunctional reagents or oxidizing agents in reactions which proceedin a largely polymer-analogous manner.

Such reactions are essentially based on modifications of the hydroxylgroups of the polyglucans by etherification, esterification or selectiveoxidation. This produces, for example, so-called starch ethers andstarch esters of the general structural formula

where R may, for example, be a hydrogen and/or an alkyl and/or aralkylradical (in the case of the starch ethers) or a hydrogen and/or anorganic and/or inorganic acid radical (in the case of the starchesters). Starch ethers and starch esters are advantageous modifiedpolysaccharides for the purposes of the present invention.

Particularly advantageous starch ethers are e.g. those obtainable byetherification of starch with tetramethylolacetylenediurea and which arereferred to as Amylum non mucilaginosum (nonswelling starch).

Also particularly advantageous are starch esters and salts thereof, forexample the sodium and/or aluminium salts of half-esters of starch whichhave low degrees of substitution, in particular sodium starch n-octenylsuccinate of the structural formula (I), in which R is characterized bythe following structure

and which is available e.g. under the trade name Amiogum® 23 fromCERESTAR, and aluminium starch octenyl succinates, in particular thoseavailable under the trade names Dry Flo® Elite LL and Dry Flo® PC fromCERESTAR.

It is advantageous to choose the average particle diameter of themodified polysaccharides used to be less than 20 μm, particularlyadvantageously less than 15 μm.

The list of said modified polysaccharides which can stabilize Pickeringemulsions according to the invention is not of course intended to belimiting. For the purposes of the present invention, modifiedpolysaccharides are obtainable in numerous ways known per se, both of achemical and a physical nature. In principle, novel ways are alsoconceivable for the preparation of modified polysaccharides according tothe invention. It is essential for the invention that the modifiedpolysaccharides display amphiphilic properties and that they do not havea thickening action.

It is further advantageous, although not obligatory, to combine theamphiphilic modified polysaccharides according to the invention withfurther amphiphilic pigments which may optionally also contribute to thestabilization of the Pickering emulsions.

Such pigments are, for example, micronized inorganic pigments chosenfrom the group of amphiphilic metal oxides, in particular from the groupconsisting of titanium dioxide, zinc oxide, silicon dioxide andsilicates (e.g. talc), where the metal oxides may be present eitherindividually or as a mixture. In this connection, it is essentiallyunimportant in which of the possible naturally occurring modificationsthe amphiphilic metal oxides used are present.

The average particle diameter of the amphiphilic metal oxides used forthe combination with polysaccharides according to the invention ispreferably chosen between 1 nm and 200 nm, particularly advantageouslybetween 5 nm and 100 nm.

It is advantageous for the purposes of the present invention to combinethe amphiphilic modified polysaccharides according to the invention withuntreated, virtually pure amphiphilic metal oxide particles, inparticular with those which can also be used as dye in the food industryand/or as absorber of UV radiation in sunscreens. Examples ofadvantageous pigments are the zinc oxide pigments which are availablefrom Merck and those which are available under the trade names Zinkoxidneutral from Haarmann & Reimer or NanoX from Harcros Chemical Group.

A further advantageous untreated pigment is boron nitride. According tothe invention, the modified polysaccharide(s) is/are preferably combinedwith one or more of the boron nitrides listed below:

Trade name available from Boron Nitride Powder Advanced Ceramics BoronNitride Powder Sintec Keramik Ceram Blanche Kawasaki HCST Boron NirtrideStark Très BN ® Carborundum Wacker-Bornitrid BNP Wacker-Chemie

The average particle diameter of the boron nitride particles used ispreferably chosen to be less than 20 μm, in particular less than 15 μm.

According to the invention, the combination of modified polysaccharideswith amphiphilic inorganic pigments which have been surface-treated(“coated”) to repel water is also advantageous, the intention being forthe amphiphilic character of these pigments to be simultaneously formedor retained. This surface treatment may involve providing the pigmentswith a thin hydrophobic layer by methods known per se.

One such process, which is described below using titanium dioxide as anexample, consists in, for example, producing the hydrophobic surfacelayer according to the following reaction

nTiO₂ +m(RO)₃Si—R′→nTiO₂(surf.)

n and m are arbitrary stoichiometric parameters, and R and R′ are thedesired organic radicals. Particularly advantageous combination partnersare TiO₂ pigments, for example those coated with aluminium stearate andavailable under the trade name MT 100 T from TAYCA.

Another advantageous coating of the combination partners consists ofdimethylpolysiloxane (also: dimethicone), a mixture of completelymethylated, linear siloxane polymers which have been terminally blockedwith trimethylsiloxy units. The combination of modified polysaccharideswith zinc oxide pigments which have been coated in this way isparticularly advantageous for the purposes of the present invention.Advantageous combination partners are also boron nitride particlestreated with dimethicone and available from Carborundum under the tradename Très BN® UHP 1106.

Advantageous coated boron nitride particles are also those treated withpolymethylhydrogensiloxane, a linear polysiloxane, which is alsoreferred to as methicone. Advantageous boron nitride particles treatedwith methicone are, for example, those available from Carborundum underthe trade name Très BN® UHP 1107.

For the purposes of the present invention, it is also favourable if theinorganic amphiphilic pigments used in addition to modifiedpolysaccharides have been coated with a mixture of dimethylpolysiloxane,in particular dimethylpolysiloxane having an average chain length offrom 200 to 350 dimethylsiloxane units, and silicagel, which is alsoreferred to as simethicone. It is particularly advantageous if theinorganic pigments have been additionally coated with aluminiumhydroxide or aluminium oxide hydrate (also: Alumina, CAS No.:1333-84-2). Particularly advantageous combination partners are titaniumdioxides which have been coated with simethicone and alumina, it alsobeing possible for the coating to contain water. One example thereof isthe titanium dioxide available under the trade name Eusolex T2000 fromMerck.

Also advantageous for the purposes of the present invention is thecombination of modified polysaccharides with a mixture of differentinorganic, amphiphilic pigment types, either within one crystal, forexample as iron mixed oxide or talc (magnesium silicate), or else bymixing two or more types of metal oxide within a preparation.Particularly advantageous combination partners are magnesium silicates,for example those available under the trade name Talkum Micron fromGrolmann.

The amphiphilic modified polysaccharides according to the invention canalso be advantageously combined with titanium dioxide pigments whichhave been coated with octylsilanol, and/or with silicon dioxideparticles which have been surface-treated to repel water. Silicondioxide particles suitable for the combination are, for example,spherical polyalkylsilsesquioxane particles, as mentioned in EuropeanLaid-Open Specification 0 686 391. Such polyalkylsilsesquioxaneparticles are, for example, those available under the trade namesAerosil R972 and Aerosil 200V from Degussa.

The modified polysaccharides are further advantageously combined withmicrofine polymer particles which are present in the preparation in theform of solids. Favourable combination partners for the purposes of thepresent invention are, for example, polycarbonates, polyethers,polyethylene, polypropylene, polyvinyl chloride, polystyrene,polyamides, polyacrylates and the like.

Combination partners which are suitable according to the invention are,for example, microfine polyamide particles, in particular thoseavailable under the trade name SP-500 from TORAY. Also advantageous arePolyamide 6 (also: Nylon 6) and Polyamide 12 (also: Nylon 12) particles.Polyamide 6 is the polyamide [poly(ε-caprolactam)] built up fromε-aminocaproic acid (6-aminohexanoic acid) or ε-caprolactam, andPolyamide 12 is a poly(ε-laurolactam) of ε-laurolactam. For the purposesof the present invention, advantageous examples are Orgasol®1002(Polyamide 6) and Orgasol® 2002 (Polyamide 12) from ELF ATOCHEM.

Further advantageous microfine polymer particles which are suitable forthe combination with modified polysaccharides are microfinepolymethacrylates. Such particles are available, for example, under thetrade name POLYTRAP® from DOW CHEMICAL.

It is particularly advantageous, although not obligatory, if themicrofine polymer particles used as combination partners have beensurface-coated. This surface treatment may involve providing the polymerparticles with a thin hydrophilic layer by processes known per se.Advantageous coatings consist, for example, of titanium dioxide (TiO₂),zirconium dioxide (ZrO₂) or else further polymers, such as, for example,polymethyl methacrylate. Particularly advantageous microfine polymerparticles for the purposes of the present invention are, for example,those available by the process described in U.S. Pat. No. 4,898,913 forthe hydrophilic coating of hydrophobic polymer particles.

The average particle diameter of the microfine polymer particles used ascombination partners is preferably chosen to be less than 100 μm,particularly advantageously less than 50 μm. In this connection, it isessentially unimportant in which form (platelets, rods, spherules etc.)the polymer particles used are present.

In all of the above cases it is advantageous to choose the totalconcentration of all the pigments to be greater than 0.1% by weight,particularly advantageously between 0.1% by weight and 30% by weight,based on the total weight of the preparations, where the concentrationof amphiphilic modified polysaccharides according to the invention is tobe chosen, for the purposes of the present invention, preferably fromthe range 0.1% by weight to 30% by weight, advantageously 0.5% by weightto 10% by weight, likewise based on the total weight of thepreparations.

The oil phase of the Pickering emulsions according to the invention isadvantageously chosen from the group of polar oils, for examaple fromthe group of lecithins and fatty acid triglycerides, namely thetriglycerol esters of saturated and/or unsaturated, branched and/orunbranched alkane carboxylic acids having a chain length of from 8 to24, in particular 12 to 18, carbon atoms. The fatty acid triglyceridesmay, for example, be advantageously chosen from the group of synthetic,semisynthetic and natural oils, such as e.g. olive oil, sunflower oil,soybean oil, peanut oil, rapeseed oil, almond oil, palm oil, coconutoil, caster oil, wheatgerm oil, grapeseed oil, thistle oil, eveningprimrose oil, macadamia nut oil and the like.

For the purposes of the present invention, further advantageous polaroil components may also be chosen from the group of esters of saturatedand/or unsaturated branched and/or unbranched alkane carboxylic acidshaving a chain length of from 3 to 30 carbon atoms and saturated and/orunsaturated, branched and/or unbranched alcohols having a chain lengthof from 3 to 30 carbon atoms, and from the group of esters of aromaticcarboxylic acids and saturated and/or unsaturated, branched and/orunbranched alcohols having a chain length of from 3 to 30 carbon atoms.Such ester oils can then advantageously be chosen from the groupconsisting of isopropyl myristate, isopropyl palmitate, isopropylstearate, isopropyl oleate, n-butyl stearate, n-hexyl laurate, n-decyloleate, isooctyl stearate, isononyl stearate, isononyl isononanoate,2-ethylhexyl palmitate, 2-ethylhexyl laurate, 2-hexyldecyl stearate,2-octyldodecyl palmitate, oleyl oleate, oleyl erucate, erucyl oleate,erucyl erucate, and synthetic, semisynthetic and natural mixtures ofsuch esters, such as e.g. jojoba oil.

In addition, the oil phase may advantageously be chosen from the groupof dialkyl ethers, the group of saturated or unsaturated, branched orunbranched alcohol. It is particularly advantageous if the oil phase ofthe W/O emulsions according to the invention has a content ofC₁₂₋₁₅-alkyl benzoate or consists entirely of this.

Any desired mixtures of such oil and wax components can also be usedadvantageously for the purposes of the present invention. In someinstances, it may also be advantageous to use waxes, for example cetylpalmitate, as the sole lipid component of the oil phase.

In addition, the oil phase of the Pickering emulsions according to theinvention may, although it is not obligatory, likewise advantageouslyalso comprise nonpolar oils, for exampel those chosen from the group ofbranched and unbranched hydrocarbons and hydrocarbon waxes, inparticular vaseline (petrolatum), paraffin oil, squalane and squalene,polyolefins and hydrogenated polyisobutenes. Of the polyolefins,polydecenes are the preferred substances.

In addition, the oil phase may advantageously have a content of cyclicor linear silicone oils, or consist entirely of such oils, although itis preferred to use an additional content of other oil phase componentsapart from the silicone oil or the silicone oils.

Advantageously, cyclomethicone (octamethylcyclotetrasiloxane) is used assilicone oil to be used according to the invention. However, othersilicone oils are also to be used advantageously for the purposes of thepresent invention, for example hexamethylcyclotrisiloxane,polydimethylsiloxane, poly(methylphenyl-siloxane).

The Pickering emulsions according to the invention can be used as basesfor cosmetic or dermatological formulations. These can have thecustomary composition and be used, for example, for the treatment andcare of the skin, as lip care product, as deodorant and as make-up ormake-up remover product in decorative cosmetics or as light protectionpreparation. For use, the cosmetic and dermatological preparationsaccording to the invention are applied to the skin in sufficient amountin the manner customary for cosmetics.

Accordingly, for the purposes of the present invention, cosmetic ortopical dermatological compositions may, depending on their structure,be used, for example, as skin-protection cream, cleansing milk,sunscreen lotion, nutrient cream, day or night cream, etc. Whereappropriate, it is possible and advantageous to use the compositionsaccording to the invention as bases for pharmaceutical formulations.

The cosmetic and dermatological preparations according to the inventionmay comprise cosmetic auxiliaries, as customarily used in suchpreparations, e.g. preservatives, bactericides, perfumes, antifoams,dyes, pigments which have a colouring effect, thickeners, plasticizers,moisturizing and/or moisture-retaining substances, fats, oils, waxes orother customary constituents of a cosmetic or dermatologicalformulation, such as alcohols, polyols, polymers, foam stabilizers,electrolytes, organic solvents or silicone derivatives.

A surprising property of the preparations according to the invention isthat they are very good vehicles for cosmetic or dermatological activeingredients into the skin, advantageous active ingredients beingantioxidants which are able to protect the skin against oxidativestress.

According to the invention, the preparations advantageously comprise oneor more antioxidants. Antioxidants which are favourable, butnevertheless optional, are all antioxidants which are suitable orcustomary for cosmetic and/or dermatological applications. Here, it isadvantageous to use antioxidants as the sole active ingredient classwhenever, for example, a cosmetic or dermatological application is atthe fore, such as e.g. the control of oxidative stressing of the skin.It is, however, also favourable to provide the stick preparationsaccording to the invention with a content of one or more antioxidantswhenever the preparations are to serve another purpose, e.g. asdeodorants or sunscreens.

The antioxidants are particularly advantageously selected from the groupconsisting of amino acids (e.g. glycine, histidine, tyrosine,tryptophan) and their derivatives, imidazoles, (e.g. urocanic acid) andtheir derivatives, peptides, such as D,L-carnosine, D-carnosine,L-carnosine and their derivatives (e.g. anserine), carotenoids,carotenes (e.g. α-carotene, β-carotene, lycopene) and their derivatives,chlorogenic acid and its derivatives, lipoic acid and its derivatives(e.g. dihydrolipoic acid), aurothioglucose, propylthiouracil and otherthiols (e.g. thioredoxin, glutathione, cysteine, cystine, cystamine andtheir glycosyl, N-acetyl, methyl, ethyl, propyl, amyl, butyl and lauryl,palmitoyl, oleyl, γ-linoleyl, cholesteryl and glyceryl esters) and theirsalts, dilauryl thiodipropionate, distearyl thiodipropionate,thiodipropionic acid and its derivatives (esters, ethers, peptides,lipids, nucleotides, nucleosides and salts) and sulphoximine compounds(e.g. buthionine sulphoximines, homocysteine sulphoximine, buthioninesulphones, penta-, hexa-, hepta-thionine sulphoximines) in very lowtolerated doses (e.g. pmol to μmol/kg), and also (metal) chelatingagents (e.g. α-hydroxyfatty acids, palmitic acid, phytic acid,lactoferrin), α-hydroxy acids (e.g. citric acid, lactic acid, malicacid), humic acid, bile acid, bile extracts, bilirubin, biliverdin,EDTA, EGTA and their derivatives, unsaturated fatty acids and theirderivatives (e.g. y-linolenic acid, linoleic acid, oleic acid), folicacid and its derivatives, ubiquinone and ubiquinol and theirderivatives, vitamin C and derivatives (e.g. ascorbyl palmitate, Mgascorbyl phosphate, ascorbyl acetate), tocopherols and derivatives (e.g.vitamin E acetate), vitamin A and derivatives (vitamin A palmitate) andconiferyl benzoate of benzoin, rutinic acid and its derivatives,α-glycosylrutin, ferulic acid, furfurylideneglucitol, carnosine,butylated hydroxytoluene, butylated hydroxyanisole, nordihydroguaiacacid, nordihydroguaiaretic acid, trihydroxybutyrophenone, uric acid andits derivatives, mannose and its derivatives, zinc and its derivatives(e.g. ZnO, ZnSO₄), selenium and its derivatives (e.g. selenomethionine),stilbenes and their derivatives (e.g. stilbene oxide, trans-stilbeneoxide), and the derivatives (salts, esters, ethers, sugars, nucleotides,nucleosides, peptides and lipids) of said active substances which aresuitable according to the invention.

The amount of the abovementioned antioxidants (one or more compounds) inthe preparations according to the invention is preferably from 0.001 to30% by weight, particularly preferably from 0.05 to 20% by weight, inparticular 1-10% by weight, based on the total weight of thepreparation.

If vitamin E and/or its derivatives are used as the antioxidant orantioxidants, their respective concentrations are advantageously chosenfrom the range of 0.001-10% by weight, based on the total weight of theformulation.

If vitamin A or vitamin A derivatives or carotenes or their derivativesare used as the antioxidant or antioxidants, their respectiveconcentrations are advantageously chosen from the range of 0.001-10% byweight, based on the total weight of the formulation.

According to the invention, the active ingredients (one or morecompounds) can also very advantageously be chosen from the group oflipophilic active ingredients, in particular from the following group:

Acetylsalicylic acid, atropine, azulene, hydrocortisone and derivativesthereof, e.g. hydrocortisone-17 valerate, vitamins, e.g. ascorbic acidand derivatives thereof, vitamins of the B and D series, very favourablyvitamin B₁, vitamin B₁₂ and vitamin D₁, but also bisabolol, unsaturatedfatty acids, namely the essential fatty acids (often also called vitaminF), in particular gamma-linolenic acid, oleic acid, eicosapentaenoicacid, docosahexanoic acid and derivatives thereof, chloramphenicol,caffeine, prostaglandins, thymol, camphor, extracts or other products ofvegetable and animal origin, e.g. evening primrose oil, borage oil orcurrant seed oil, fish oils, cod-liver oil or also ceramides andceramide-like compounds and so on.

It is also advantageous to choose the active ingredients from the groupof refatting substances, for example purcellin oil, Eucerit□ andNeocerit□.

The list of said active ingredients or active ingredient combinationswhich can be used in the Pickering emulsions according to the inventionis not of course intended to be limiting.

Cosmetic and dermatological preparations which are in the form of asunscreen are also favourable. These preferably comprise at least oneUV-A filter substance and/or at least one UV-B filter substance and/orat least one further inorganic pigment selected from the groupconsisting of the oxides of iron, zirconium, silicon, manganese,aluminium, cerium and mixtures thereof and also modifications in whichthe oxides are the active agents.

For the purposes of the present invention, it is, however, alsoadvantageous to provide such cosmetic and dermatological preparationswhose main purpose is not protection against sunlight, but whichnevertheless comprise substances which protect against UV. For example,UV-A and UV-B filter substances are commonly incorporated into daycream.

The preparations according to the invention can advantageously comprisefurther substances which absorb UV radiation in the UV-B range, thetotal amount of filter substances being, for example, from 0.1% byweight to 30% by weight, preferably from 0.5 to 10% by weight, based onthe total weight of the preparations, in order to provide cosmeticpreparations which protect the hair and/or the skin from the wholeregion of ultraviolet radiation.

If the emulsions according to the invention contain UV-B filtersubstances, the latter may be oil-soluble or water-soluble. Examples ofoil-soluble UV-B filters which are advantageous according to theinvention are:

ξ 3-benzylidenecamphor derivatives, preferably3-(4-methylbenzyl-idene)camphor, 3-benzylidenecamphor;

ξ 4-aminobenzoic acid derivatives, preferably 2-ethylhexyl4-(dimethylamino)benzoate, amyl 4-(dimethylamino)benzoate;

ξ esters of cinnamic acid, preferably 2-ethylhexyl 4-methoxycinnamate,isopentyl 4-methoxycinnamate;

ξ esters of salicylic acid, preferably 2-ethylhexyl salicylate,4-isopropylbenzyl salicylate, homomenthyl salicylate;

ξ derivatives of benzophenone, preferably2-hydroxy4-methoxybenzophenone,2-hydroxy-4-methoxy-4′-methylbenzophenone,2,2′-dihydroxy-4-methoxy-benzophenone;

ξ esters of benzalmalonic acid, preferably di(2-ethylhexyl)4-methoxy-benzalmalonate;

ξ triazine derivatives symmetrically or unsymmetrically substituted withregard to the C₃ axis of the parent triazine substance, preferablytris(2-ethylhexyl)4,4′,4″-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate (symmetrical)and2,4-bis⊥[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}6-(4-methoxyphenyl)-1,3,5-triazine,2,4-bis{[4-(3-sulphonato)-2-hydroxypropyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)-1,3,5-triazinesodium salt,2,4-bis{[4-(3-(2-propyloxy)-2-hydroxypropyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)-1,3,5-triazine,2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-[4-(2-methoxyethylcarboxyl)phenylamino]-1,3,5-triazine,2,4-bis{[4-(3-(2-propyloxy)-2-hydroxypropyloxy)-2-hydroxy]-phenyl}6-[4-(2-ethylcarboxyl)phenylamino]-1,3,5-triazine,2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-(1-methylpyrrol-2-yl)-1,3,5-triazine,2,4-bis{[4-tris(trimethyl-syloxysilylpropyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)-1,3,5-triazine,2,4-bis{[4-(2″-methylpropenyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)-1,3,5-triazine,2,4-bis{[4-(1′,1′,1′,3′,5′,5′,5′-heptamethylsiloxy-2-methylpropyloxy)-2-hydroxy]phenyl}6-(4-methoxyphenyl)-1,3,5-triazine(unsymmetrical),

ξ benzotriazole derivatives, preferably2,2′-methylenebis(6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol)

ξ and UV filters bonded to polymers.

Examples of advantageous water-soluble UV-B filters are:

ξ Salts of 2-phenylbenzimidazole-5-sulphonic acid, such as its sodium,potassium or its triethanolammonium salt, and also the sulphonic aciditself;

ξ Sulphonic acid derivatives of 3-benzylidenecamphor, such as e.g.4-(2-oxo-3-bomylidenemethyl)benzenesulphonic acid,2-methyl-5-(2-oxo-3-bornylidene-methyl)sulphonic acid and their salts.

The list of said UV-B filters, which may be used in the Pickeringemulsions according to the invention, is of course not intended to belimiting.

It can also be advantageous to use, in the Pickering emulsions accordingto the invention, UV-A filters which have hitherto been customarilypresent in cosmetic preparations. These substances are preferablyderivatives of dibenzoylmethane, in particular1-(4′-tert-butylphenyl)-3-(4′-methoxyphenyl)propane-1,3-dione and1-phenyl-3-(4′-isopropylphenyl)propane-1,3-dione.

Further advantageous UV-A filter substances arephenylene-1,4-bis(2-benzimidazyl)3,3′-5,5′-tetrasulphonic acid:

and its salts, particularly the corresponding sodium, potassium ortriethanolammonium salts, in particularphenylene-1,4-bis(2-benzimidazyl)-3,3′-5,5′-tetrasulphonic acidbis-sodium salt:

and 1,4-di(2-oxo-10-sulpho-3-bomylidenemethyl)benzene and salts thereof(in particular the corresponding 10-sulphato compounds, in particularthe corresponding sodium, potassium or triethanolammonium salt), whichis also referred to asbenzene-1,4-di(2-oxo-3-bornylidenemethyl-10-sulphonic acid) and ischaracterized by the following structure:

Advantageous UV filter substances are also so-called broad-band filters,i.e. filter substances which absorb both UV-A and UV-B radiation.

A broad-band filter which is to be used advantageously is, for example,ethylhexyl 2-cyano-3,3-diphenylacrylate (octocrylene), which isobtainable from BASF under the name Uvinul® N 539 and is characterizedby the following structure:

Preparations which contain UV-A filters or so-called broad-band filtersare also provided by the invention. The amounts which may be used are asfor the UV-B combination.

Preparations which contain UV-A filters or so-called broad-band filtersare also provided by the invention. The amounts which may be used are asfor the UV-B combination.

Preparations according to the invention can also be advantageously usedas bases for cosmetic deodorants and antiperspirants, so that aparticular embodiment of the present invention relates to Pickeringemulsions as bases for cosmetic deodorants.

Cosmetic deodorants are used to control body odour which arises whenfresh sweat, which is in itself odourless, is decomposed bymicroorganisms. Customary cosmetic deodorants are based on various modesof action.

In antiperspirants, astringents, mainly aluminium salts, such asaluminium hydroxychloride (aluchlorhydrate), reduce sweat production.

The use of antimicrobial substances in cosmetic deodorants can reducethe bacterial flora of the skin. In an ideal situation, only themicroorganisms which cause the odour should be effectively reduced. Theflow of sweat itself is not influenced as a result, and in idealcircumstances, only microbial decomposition of sweat is stoppedtemporarily.

The combination of astringents and antimicrobial substances in one andthe same composition is also common.

All active ingredients common for deodorants or antiperspirants canadvantageously be used, for example odour concealers, such as customaryperfume constituents, odour absorbers, for example the phyllosilicatesdescribed in Patent Laid-Open Specification DE 40 09 347, of these inparticular montmorillonite, kaolinite, illite, beidellite, nontronite,saponite, hectorite, bentonite, smectite, and also, for example, zincsalts of ricinoleic acid. Antibacterial agents are also suitable forincorporation into the W/O emulsion sticks according to the invention.Advantageous substances are, for example, 2,4,4′-trichloro-2′-hydroxydiphenyl ether (Irgasan), 1,6-di(4-chlorophenylbiguanido)hexane(chlorhexidine), 3,4,4′-trichlorocarbanilide, quatemary ammoniumcompounds, oil of cloves, mint oil, thyme oil, triethyl citrate, Famesol(3,7,1 1-trimethyl-2,6,10-dodecatrien-1-ol), and the active ingredientsor active ingredient combinations described in Patent Laid-OpenSpecifications DE-37 40 186, DE-39 38 140, DE-42 04 321, DE-42 29 707,DE-43 09 372, DE-44 11 664, DE-195 41 967, DE-195 43 695, DE-195 43 696,DE-19547 160, DE-196 02108, DE-196 02110, DE-196 02111, DE-196 31 003,DE-196 31 004 and DE-196 34 019, and Patent Specifications DE-4229737,DE-42 37 081, DE-43 24219, DE-4 29467, DE-44 23410 and DE-195 16 705.Sodium hydrogencarbonate can also be used advantageously.

The list of said active ingredients or active ingredient combinationswhich can be used in the Pickering emulsions according to the inventionis not of course intended to be limiting.

The cosmetic deodorants according to the invention can be present in theform of hydrous, cosmetic preparations which can be applied from normalcontainers.

The amount of antiperspirant active ingredients or deodorants (one ormore compounds) in the preparations is preferably 0.01 to 30% by weight,particularly preferably 0.1-20% by weight, in particular 1-10% byweight, based on the total weight of the preparation.

The sticks according to the invention are also excellent vehicles fordermatological active ingredients. In particular, they are suitable ascarriers for substances effective against acne. Acne is a skin disorderof many different forms and causes, characterized by non-inflamed andinflamed bumps, originating from blocked hair follicles (comedones)which can lead to the formation of pustules, abscesses and scars. Themost frequent is Acne vulgaris which occurs mainly in puberty. Causativeconditions for Acne vulgaris are the keratinization and blocking of thehair follicle opening, the production of sebum, which is dependent onthe level of male sex hormones in the blood, and the production of freefatty acids and tissue-damaging enzymes by bacteria (Propionibacteriumacnes).

It is therefore advantageous to add to the preparations according to theinvention substances effective against acne which are effective, forexample, against Propionibacterium acnes (for example those described inDE-A 42 29 707, DE-A 43 05 069, DE-A 43 07 976, DE-A 43 37 711, DE-A 4329 379), but also other substances which are effective against acne, forexample all-trans-retinoic acid, 13-cis-retinoic acid and relatedsubstances) or anti-inflammatory active ingredients, for example batylalcohol (α-octadecyl glyceryl ether), selachyl alcohol (α-9-octadecenylglyceryl ether), chimyl alcohol (α-hexadecyl glyceryl ether) and/orbisabolol, and antibiotics and/or keratolytics.

Keratolytics are substances which soften keratinized skin (such as e.g.warts, corns, calluses and the like) so that it can be removed moreeasily or so that it falls off or peels off.

All of the common substances effective against acne can be usedadvantageously, in particular benzoyl peroxide, bituminosulphonates(ammonium, sodium and calcium salts of shale oil sulphonic acids),salicylic acid (2-hydroxybenzoic acid), miconazole(1-[2-(2,4-dichlorobenzyloxy)-2-(2,4-dichloro-phenyl)ethyl]imidazole)and derivatives, adapalene(6-[3-(1-adamantyl)-4-methoxyphenyl]-2-naphthoic acid), azelaic acid(nonanedioic acid), mesulphene (2,7-dimethylthianthrene, C₁₄H₁₂S₂), andaluminium oxide, zinc oxide and/or finely dispersed sulphur.

The amount of antiacne agents (one or more compounds) in thepreparations is preferably 0.01 to 30% by weight, particularlypreferably 0.1-20% by weight, in particular 1-10% by weight, based onthe total weight of the preparation.

The following examples serve to illustrate the present invention,without limiting it. The numerical values in the examples indicatepercentages by weight, based on the total weight of the respectivepreparations.

EXAMPLES

1 2 3 4 5 6 W/O W/O W/O O/W O/W O/W Titanium dioxide 4 6 2 2 (EusolexT2000) Zinc oxide 4 4 Silica (Aerosil R972) 1 0.5 Talc (Talkum Micron) 2Boron nitride 1 Sodium corn starch n-octenyl 2 1 2 5 1 1 succinateOrgasol ® 1002 1 1 (Polyamide 6) Caprylic/capric triglyceride 5 5 5 2020 20 Octyldodecanol 10 5 20 15 Mineral oil 10 5 20 20 Butylene glycol10 10 20 7 caprylate/caprate C₁₂₋₁₅-alkyl benzoate 10 10 10 5 20Methylbenzylidenecamphor 3 4 Octyltriazone 1 4 Dibenzoylmethane 2 2Preservative 0.5 0.5 0.5 0.5 0.5 0.5 Glycerol 5 10 3 5 5 5Phenylbenzimidazolsulphonic 1 2 acid Carbomer 0.1 NaOH 45% strengthsolution 0.3 0.1 1.3 in water EDTA solution 1 1 Water ad ad ad ad ad ad100 100 100 100 100 100

What is claimed is:
 1. Cosmetic or dermatological preparations, which are finely dispersed, hydrocolloid-free oil-in-water or water-in-oil systems, comprising (i) an oil phase, (ii) an aqueous phase, (iii) at least one modified polysaccharide which (a) has both hydrophilic and lipophilic properties and is dispersible both in water and in oil, and which (b) has no thickening properties, (c) is present in an amount from 1-30% by weight, and wherein the preparations are emulsifier-free.
 2. Preparations according to claim 1, characterized in that further cosmetic or pharmaceutical auxiliaries, additives and/or active ingredients are present.
 3. Preparations according to claim 1, characterized in that the average particle diameter of the modified polysaccharides used is less than 20 μm.
 4. Preparations according to claim 1, characterized in that the modified polysaccharide(s) is/are selected from the group of starch ethers and starch esters.
 5. Preparations according to claim 1, characterized in that, in addition to modified polysaccharides, further amphiphilic pigments are present it being possible for these further amphiphilic pigments to be present either individually or else as a mixture.
 6. Preparations according to claim 1, comprising one or more additives or active substances selected from the group consisting of antioxidants and UV protectants.
 7. Preparations according to claim 1, comprising one or more additives or active substances selected from the group consisting of astringents, antimicrobials, and substances effective against acne.
 8. Preparations according to claim 4, characterized in that the average particle diameter of the modified polysaccharides used is less than 15 μm.
 9. Preparations according to claim 6, wherein said further amphiphilic pigments are selected from the group consisting of microfine polymer particles; micronized, inorganic pigments; and mixtures thereof.
 10. Preparations according to claim 9, wherein said micronized, inorganic pigments which are amphiphilic metal oxides.
 11. Preparations according to claim 10, wherein said amphiphilic metal oxides are selected from the group consisting of titanium dioxide, zinc oxide, iron oxides or iron mixed oxides, silicon dioxide and silicates. 